Theoretical Investigation of Proton Diffusion in Dion–Jacobson Layered Perovskite RbBiNb2O7

Abstract

Perovskite materials are considered to be promising electrolyte membrane candidates for electrochemical applications owing to their excellent proton- or oxide-ion-conducting properties. RbBiNb2O7 is a double-layered Dion–Jacobson perovskite oxide, with Pmc21 symmetry. In this study, the electronic structure and proton-diffusion properties of bulk RbBiNb2O7 were systematically investigated using first-principles calculations. The unique layered crystal structure of RbBiNb2O7 plays a crucial role in proton storage and proton conductivity. Different proton-diffusion steps in RbBiNb2O7 were considered, and the activation energies of the relevant diffusion steps were evaluated using the climbing image-nudged elastic band (CI-NEB) technique. The proton diffusion in RbBiNb2O7 presents a two-dimensional layered characteristic in the a-b plane, owing to its layered crystalline nature. According to the transition state calculations, our results show that the bulk RbBiNb2O7 exhibits good proton-transport behavior in the a-b plane, which is better than many perovskite oxides, such as CaTiO3, CaZrO3, and SrZrO3. The proton diffusion in the Rb–O and Nb–O layers is isolated by a higher energy barrier of 0.86 eV. The strong octahedral tilting in RbBiNb2O7 would promote proton transport. Our study reveals the microscopic mechanisms of proton conductivity in Dion–Jacobson structured RbBiNb2O7, and provides theoretical evidence for its potential application as an electrolyte in solid oxide fuel cells (SOFCs).

Kinetics of Ions in Post-Lithium Batteries

“…It is observed from Table 1 that NaZr 2 (PO 4 ) 3 (known as NZP-it is NASICON-type) has a very low activation energy of diffusion (0.26 eV) [47]. These static atomistic simulations are in agreement with previous molecular dynamic calculations by Zou et al [20] that calculated activation energy for Na diffusion of 0.23 eV.Figure 1 is a schematic representation of the long-range Na-ion diffusion and the migration energy profile for the Na pathway in NaZr 2 (PO 4 ) 3 [47]. DFT simulations indicate that NaZr 2 (PO 4 ) 3 is a wide-gap semiconductor, however, the exoergic incorporation of sodium leads to Na + ions and electrons.…”

Design of Mixed Ionic-Electronic Materials for Permselective Membranes and Solid Oxide Fuel Cells Based on Their Oxygen and Hydrogen Mobility

“…Various types of oxide materials, which possess ionic conductivity due to cooperative oxygen migration mechanisms involving the cooperative motion of some forms of oxygen, can be used as SOFC electrolytes or, as a composite with electronically conductive or MIEC materials, as SOFC electrodes and oxygen separation membranes (or their permselective layers). Amongst these materials, doped La silicates/germanates with the apatite structure [ 58 , 69 , 107 , 134 , 325 ] ( Figure 24 ), alkaline-earth-metal-doped La gallates with β-K 2 SO 4 structure ( Figure 25 ) [ 107 , 134 , 326 ], alkaline-earth metal ferrites, cobaltites, aluminates, gallates and indates with a brownmillerite structure ( Figure 26 ) [ 107 , 134 , 327 , 328 ], M 3−x M’ x Ti 2 NbO 10−δ (M = Na, Ca, Cs; M = Bi, Ln, Rb) with a Dion–Jacobson-type layered perovskite structure [ 329 , 330 , 331 ], etc. [ 55 , 58 , 60 , 69 ] are to be mentioned.…”

Design of Mixed Ionic-Electronic Materials for Permselective Membranes and Solid Oxide Fuel Cells Based on Their Oxygen and Hydrogen Mobility

“…Various types of oxide materials, which possess ionic conductivity due to cooperative oxygen migration mechanisms involving cooperative motion of some forms of oxygen, can be used as SOFC electrolytes or, as a composite with electronically conductive or MIEC materials, as SOFC electrodes and oxygen separation membranes (or their permselective layers). Amongst these materials, doped La silicates/germanates with the apatite structure [62,75,91,93,271] (Figure 19), alkaline-earth metal doped La gallates with β-K2SO4 structure (Figure 20) [91,93,272], alkaline-earth metal ferrites, cobaltites, aluminates, gallates and indates with a brownmillerite structure (Figure 21) [91,93,273,274], M3-xM'xTi2NbO10−δ (M = Na, Ca, Cs; M = Bi, Ln, Rb) with a Dion-Jacobson-type layered perovskite structure [275][276][277], etc. [54,62,64,75] are to be mentioned.…”